An example of a related-art invention is Japanese Patent Application Laid-Open No. HEI05-190342 (Patent Document 1). Patent Document 1 discloses a wound core transformer and a method for fabricating the same and aims to simplify the work of covering the wound core, which is made of an amorphous magnetic alloy, and also aims to prevent the leakage of broken core fragments. The transformer disclosed therein comprises core covers having cylinders to insert legs of the wound core and flanges provided at both ends of the cylinder, and the cylinders of these core covers are inserted into the windows of a coil. The joint sections of one of the yokes of the wound core are then disconnected so that the legs of the wound core are inserted into the cylinders of the core covers. After the insertion of the wound core legs, the joint sections of the core are closed. Thereafter, the flanges of the core covers are folded to cover the yokes of the wound core.